development and achievement of the t-50 flight … and achievement of the t-50 flight control’s...
TRANSCRIPT
Journal of Aerospace Science and Technology 1 (2015) 67-72 doi: 10.17265/2332-8258/2015.02.003
Development and Achievement of the T-50 Flight
Control’s Consolidated OFP
Soon Ryong Jang, In Je Cho and Byung Moon Hwang
Flight Control Team, Korea Aerospace Industries, LTD., Sacheon, Korea
Abstract: The OFP (operational flight program) of the digital fly-by-wire FCS (flight control system) system is safety-critical item and has to be designed and verified to assure the safety of flight based on tightly coupled process. T-50 FCS OFP interacts with triplex redundant FCS system and other major subsystem including avionics. So far, the multi-version of FCS OFP has been developed and serviced per each T-50 derivatives’ requirements. The consolidation of OFP was demanded to save development cost and schedule, by concurrent release to service all T-50 derivatives when general improvement is requested. Through successful developing the Plug & Play type OFP, it is possible to maintain the single configuration of FCS OFP as well as compatibility with dissimilar avionics of each T-50’s derivatives. In this paper, we present the development process, results and achievement of the consolidated FCS OFP. Key words: FCS, OFP, Plug & Play type.
1. Introduction
The flight control system and OFP of a highly
maneuverable fighter class aircraft is critical item
which directly impacts on aircraft safety. Flight control
software controls or monitors hardware whose
reliability or performance directly impacts on the
PLOC (probability-of-loss of control), survivability,
aircraft performance (stability & handling qualities)
and crew safety (structural, loads, and human
limitations) [1].
T-50 Flight control system design encompasses the
interface with major subsystem to acquire the accurate
control and integrity. The major interacting subsystem
consists of hydraulic, electrical, avionics, engine,
landing gear, cockpit system, etc., and also support
equipment. The T-50 was originally developed for
LIFT (lead-in fighter like trainer), modified to TA-50
supporting CAS (close air combat) mission, and
finally upgraded to the FA-50 for air to air combat
mission and electric warfare. Other variants are
T-50B for ROKAF acrobatic team, T-50i for
Corresponding author: Soon Ryong Jang, flight control
system design lead & senior research engineer, main research field : flight control system, safety critical software mechanization. E-mail: [email protected].
Indonesian AF (air force), FA-50PH based on FA-50
for Philippine AF. To satisfy the customer
requirement of these T-50 variants, aircraft subsystem
including flight control system need to improve. Most
of changes so far are generally required in the avionics
system.
In this paper, development and achievement of the
plug & play type consolidated flight control OFP are
addressed. Through successful developing the Plug &
Play type OFP, it is possible to maintain the single
configuration of FCS OFP as well as compatibility with
dissimilar avionics of each T-50’s derivatives. In this
paper, we present the development process, results and
achievement of the consolidated FCS OFP as a best
practice.
2. Consolidated OFP’s Needs
The flight control system is responsible for
controlling flight, attitude and safety. The avionics
system is responsible for
communication/navigation/weapon/display,
inter-commuting the aircraft information (air data,
motion and states) for weapon delivery, navigation
and the navigation, pilot display interface for fine
control and autopilot mode via MIL-STD-1553B
D DAVID PUBLISHING
68
MUX Bus.
computer) fa
highly reliab
device, will
maintaining
Bus. Throu
primary dis
weapon deli
mission com
As a resul
or improved
bus control
control OFP
background
proposed to
requirement
version for
well as sav
effort in the
study, the a
were selecte
T-50 series
signals hav
switch the
variant.
3. Develo
Fig. 1 Aircr
Develo
When the
fails, the FLC
ble, safe and
provide back
g transaction
gh this safe
play, naviga
ivery missio
mputer loss.
lt of that, wh
d the avionic
design beco
P and this imp
d, the consoli
integrate all
t but maint
assuring flig
ving mainten
e life cycle. F
addition of 4
ed to identify
as shown in F
ve triplex re
proper conf
opment an
aft wiring desi
opment and A
IMDC (inte
CC (flight con
high comput
kup bus contr
on the Avio
ty feature, t
ation, flight d
n are able to
hen each varia
cs system de
mes dissimil
pacts the inte
dated flight c
l variants’ ba
ain the sing
ght safety cr
nance cost a
From the resu
independent
y each varian
Fig. 1 [2]. Th
edundancy a
figuration da
nd Achieve
ign for the airc
Achievement o
egrated mis
ntrol compute
ting performa
rol capability
onics 1553 M
the engine, p
data record,
o continue un
ant has expan
sign, the bac
lar in each fl
erface. From
control OFP
ckup bus con
gle or comm
ritical featur
and developm
ults of a trad
t aircraft sig
nt or block of
he 4 independ
and are used
atabase per e
ement of
craft identifica
of the T-50 Fl
sion
er), a
ance
y for
MUX
pilot
and
nder
nded
ckup
light
this
was
ntrol
mon
re as
ment
deoff
gnals
f the
dent
d to
each
the
Co
T
of p
whi
and
T
sum
A
iden
airc
and
Pow
Mo
and
the
mod
the
app
airc
enc
des
S
sign
iden
wir
ation.
light Control’
nsolidate F
The below Fig
plug & play
ich will comp
d subsystems.
The design fe
mmarized in th
Aircraft wiri
ntification c
craft wirings a
d select the
wer up CSC
dule will dete
d initialize all
flight contr
dule and prov
subsystem
propriating p
craft identific
ompasses th
ign features.
Signal manag
nal fault dete
ntification by
ing input sig
’s Consolidat
Flight Cont
g. 2 is to show
type, consoli
patible with m
feature for ea
he following
ing module
code using
and input to th
aircraft iden
C (compute
ermine the pro
l internal par
rol computer
visional CSC
m interface
parameter da
cation at po
he other var
gement CSC
ection monito
y voting rule a
nal as discret
ted OFP
trol OFP
w the concept
idated flight
multiple dissim
ach functiona
.
is to imp
independent
he flight cont
ntification c
er software
oper aircraft i
rameter durin
r. The AVS
will determin
parameter
atabase per
ower up sta
riant-depende
module will
or and select
after receivin
te type. Built
tual structure
control OFP
milar aircraft
al module is
plement the
t, redundant
trol computer
onfiguration.
component)
identification
ng boot up of
S 1553 CSC
ne and switch
with the
preselected
ge and also
ent potential
perform the
t the aircraft
ng the aircraft
t-in-test CSC
e
P
t
s
e
t
r
.
)
n
f
C
h
e
d
o
l
e
t
t
C
Fig. 2 Conce
Module is
checkout sta
correctness
identificatio
the each mo
ready for flig
Failure M
failure detec
resulting fro
It will analy
isolate the f
report the fa
with cautio
advisory and
corrective ac
NVM CS
related to the
operation fr
sources for m
under any tr
Develo
eptual structur
generally in
age for the flig
of initializ
n and its data
odule proces
ght or not.
Management C
ction reportin
om Signal Ma
yze the fault
fault to preve
ault isolation
on lamp and
d displays. Th
ction in accor
C Module wi
e fault of airc
rom misconf
maintaining th
ransient or em
opment and A
re of the conso
nitiated by p
ght mission. I
zed and con
abase, and als
ssing of cons
CSC Module
ng and diagno
anagement CS
t impact at t
ent the fault
results to the
d fault code
hen pilot or o
rdance with f
ill record all
craft identifica
figuration an
he aircraft ide
mergency situ
Achievement o
olidated OFP.
pilot at prefl
It will validate
nfigured airc
o checks whe
solidated OF
e will process
ostic informa
SC and BIT C
the system le
propagation
e pilot or oper
es using coc
operator will
fault reporting
diagnostic da
ation or impro
nd all referen
entification v
uation. This
of the T-50 Fl
flight
e the
craft
ether
FP is
s the
ation
CSC.
evel,
and
rator
ckpit
take
g.
atum
oper
nced
value
data
will
of
con
con
last
ope
che
mis
T
dev
(saf
The
com
(sys
con
P
leve
hard
com
For
light Control’
l used to trou
the systemat
ntrol) will dis
ntains the T-5
t text. From
erator can ins
ecking aircraf
ssion.
The flight an
velopment th
fety-of-flight
e validation
mpleted w
stem/software
nsolidated flig
Per the above
el unit test
dware/softwa
mpleted with r
r further design
’s Consolidat
ubleshoot and
tic fault. IU
splay the flig
0 variant’s ai
this positive
spect the FCS
ft identity co
nd safety cri
horoughly fo
certificate) p
and verifica
without any
e product a
ght control OF
SOF certifica
t was comp
are integratio
real time and r
n validation p
ted OFP
investigate th
UFC (integrat
ht control OF
ircraft identit
e design feat
S OFP worki
ode prior to
itical flight
ollow the p
process as sho
ation activitie
y hazardo
anomaly rep
FP.
ation process,
pletely pass
on test was
real platform
purpose, SFM
69
he root cause
ted up front
FP ID which
ty code at the
ture, pilot or
ing status by
every flight
control OFP
proven SOF
own in Fig. 3.
es had been
ous SPAR
ort) for the
, the software
sed and the
successfully
environment.
MEA (software
9
e
t
h
e
r
y
t
P
F
.
n
R
e
e
e
y
.
e
Development and Achievement of the T-50 Flight Control’s Consolidated OFP
70
Fig. 3 Safety of flight certification flow for flight critical FCS OFP.
failure mode effect analysis) was performed to identify
the potential hazard of the consolidated OFP and
incorporate those hazard cases into design validation
test procedure [3].
Since each variant OFP configuration matching with
aircraft identification should be verified per flight
critical FCS OFP development process, conceptually
total demands of test schedule and effort are multiplied
by the number of variants. The V&V (validation and
verification) test for flight control OFP is composed of
three different test categories. The first test is SAVV
(stand-alone test), FCS (unit under test) in an open loop
environment to verify the software functional
requirements. The second test is ISVV (integrated
system test), hardware-in-the-loop integration
simulation used to evaluate the flight-worthiness,
handling qualities of the flight control OFP and
verify the control laws design change. The last test is
FMET (failure modes & effects test) which
demonstrates the flight controls’ robustness in the
presence of failures.
To mitigate this development’s cost and schedule
risk, a trade off study was performed to optimize the
V&V test case and schedule plan. According to the
study results, the V&V test cases were categorized into
four different classes and finally 66% of total V&V test
cases were saved as shown in Table 1.
Category 1—Affective: Test cases were impacted by
each variant configuration;
Category 2—Common: Common test cases not
included in Category 1 and independent of variant
configuration;
Category 3—Essential: Mandatory test case
regardless of change in the FCS OFP;
Development and Achievement of the T-50 Flight Control’s Consolidated OFP
71
Table 1 Comparison of V&V test cases.
Test category Savv Isvv Tmet
Affected test cases 30 52 34
Common test cases 369 0 68
Essential test cases 96 47 0
Special test cases 0 319 4
Target AC IDs 2 2 2
No. of pilot 1 2 1
Single OFP total cases 495 94 106
Consolidate OFP total cases 621 146 144
Test increased rate 126%
Fig. 4 Estimated life-cycle maintenance cost benefits
Category 4—Special: Test cases for verify the
design change on this version, temporary check;
From the optimization of development and verification
activities for developing the consolidated FCS OFP, it
is possible that not only multiple and dissimilar
customer requirements can be accepted but also
development schedule and effort can be dramatically
saved. From the statistic records, the maintenance cost
for the FCS OFP in the life cycle was estimated as
shown in Fig. 4.
3. Conclusion
The flight control OFP was successfully developed
which is plug & play type and compatible with
dissimilar multiple requirement. To assure the safety
and reliability of flight critical FCS OFP, the proven
SOF Certification process was applied to the life cycle
of FCS OFP development. Through the efforts and
results of consolidated FCS OFP and process, it is
possible that the development effort, schedule and
maintenance cost could be saving up to approximately
30%-40% down versus those from existing FCS OFP
way. When ROKAF (Rep. of Korea Air Force) and
international customer request design improvement or
new requirement in the next, single and consolidate
FCS OFP can cover all dissimilar requirements of each
Development and Achievement of the T-50 Flight Control’s Consolidated OFP
72
variant simultaneously at the same time.
References
[1] Jang, S. R. 2012. “Digital Flight Control Software Verification Test Technology.” DAPA Weapon System Software Conference, Seoul, Korea.
[2] Jang, S. R., and Seo, S. J. 2013. “Development of the Plug & Play Type Flight Control OFP as per Aircraft Derivatives.” KSAS Conference, Yong-pyung, Korea.
[3] Cho, S. H., and Jang, S. R. 2014. “Design Safety Advancement of the Common Flight Control OFP through Enhanced SFMEA Process Modeling.” SASE Autumn Conference, Mu-ju, Korea.